Perovskite as nickel catalyst precursor – impact on catalyst stability on xylose aqueous-phase hydrogenation

Abstract

Precursors materials with formula, La_1−xCe_xAl_0.18Ni_0.82O₃ (x = 0.0, 0.1, 0.5, 0.7), were successfully used as precursors to prepare Ni nanoclusters to be used as catalysts in the hydrogenation of xylose to xylitol. For the Ce free and lower Ce content (x = 0.0; 0.1), the perovskite structure was obtained, whereas for a higher Ce content (x = 0.5; 0.7), an ordinary CeO₂–La₂O₃ solid dissolution with no perovskite structure were obtained. Under the reduction conditions, the perovskite structure leads to ∼30% of metallic Ni without any loss of the perovskite structure (x = 0.0; 0.1) and the CeO₂–La₂O₃ solid dissolution allows a Ni reduction of ∼40% of Ni (x = 0.5; 0.7). As expected, the similar reduced Ni content does not show large differences in the aqueous-phase xylose hydrogenation product distribution, or large difference in the precursors. The perovskite structure (x = 0.0; 0.1) and solid dissolution (x = 0.5; 0.7) highlight the importance of the perovskite structure in the remarkable leaching resistance showed by the Ni perovskite-precursor (x = 0.0; 0.1) catalysts, showing no Ni leaching over 6 h of reaction in an aqueous medium.